title: Up-regulation of heme oxygenase-1 contributes to the amelioration of aluminum-induced oxidative stress in Medicago sativa.
abstract: In this report, pharmacological, histochemical and molecular approaches were used to investigate the effect of heme oxygenase-1 (HO-1) up-regulation on the alleviation of aluminum (Al)-induced oxidative stress in Medicago sativa. Exposure of alfalfa to AlCl3 (0-100 μM) resulted in a dose-dependent inhibition of root elongation as well as the enhancement of thiobarbituric acid reactive substances (TBARS) content. 1 and 10 μM (in particular) Al(3+) increased alfalfa HO-1 transcript or its protein level, and HO activity in comparison with the decreased changes in 100 μM Al-treated samples. After recuperation, however, TBARS levels in 1 and 10 μM Al-treated alfalfa roots returned to control values, which were accompanied with the higher levels of HO activity. Subsequently, exogenous CO, a byproduct of HO-1, could substitute for the cytoprotective effects of the up-regulation of HO-1 in alfalfa plants upon Al stress, which was confirmed by the alleviation of TBARS and Al accumulation, as well as the histochemical analysis of lipid peroxidation and loss of plasma membrane integrity. Theses results indicated that endogenous CO generated via heme degradation by HO-1 could contribute in a critical manner to its protective effects. Additionally, the pretreatments of butylated hydroxytoluene (BHT) and hemin, an inducer of HO-1, exhibited the similar cytoprotective roles in the alleviation of oxidative stress, both of which were impaired by the potent inhibitor of HO-1, zinc protoporphyrin IX (ZnPP). However, the Al-induced inhibition of root elongation was not influenced by CO, BHT and hemin, respectively. Together, the present results showed up-regulation of HO-1 expression could act as a mechanism of cell protection against oxidative stress induced by Al treatment.
authors.affiliation: College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province 210095, China.
authors.forename: Weiti
authors.initials: W
authors.lastname: Cui
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Xuan
authors.forename: Yanjie
authors.initials: Y
authors.lastname: Xie
mesh_terms: D000535:Aluminum / Q000633:toxicity*; D051547:Heme Oxygenase-1 / Q000378:metabolism*; D000455:Medicago sativa / Q000187:drug effects* / Q000201:enzymology*; D018384:Oxidative Stress / Q000187:drug effects*; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D000535:Aluminum; D051547:Heme Oxygenase-1
keywords: APX; ASC; Al; Aluminum toxicity; BHA; BHT; BR; BV; CAT; CO; Carbon monoxide; G6PDH; GPX; GR; GST; HO; HO-1; Heme oxygenase-1; Medicago sativa; NO; Oxidative stress; POD; ROS; SOD; TBARS; ZnPP; aluminum; ascorbate peroxidase; ascorbic acid; bilirubin; biliverdin; butylated hydroxyanisole; butylated hydroxytoluene; carbon monoxide; catalase; glucose-6-phosphate-dehydrogenase; glutathione S-transferase; glutathione peroxidase; glutathione reductase; guaiacol peroxidase; heme oxygenase; heme oxygenase-1; nitric oxide; reactive oxygen species; superoxide dismutase; thiobarbituric acid reactive substances; zinc protoporphyrin IX